Is Lobster a fish?

In this post, we will answer the question “Is Lobster a fish?”. We will also understand and learn more about the Lobsters biology and ecology.  

Is Lobster a fish?

No, Lobsters are not fish. They are arthropods members of the crustacean class. Lobsters are classified into the order of the decapods in the Nephropidae family. There are more than 50 species of Lobsters. 

Lobster armour

With a rigid exoskeleton composed mainly of chitin, Lobsters undergo moulting processes. During the moulting, they break the old carapace and form a new one with increased size. During this process, changes in the animal’s colour are normal. These variations are caused by the gradual biosynthesis of astaxanthin, the main pigment in the Lobster exoskeletons. However, rare species of lobster with different colours, other than red or orange (the most common), can be sold for high values for aquariums. These exotic colours include albino, blue, pink, yellow, and spotted lobsters with a colour mixture. 

Body division

The anterior portion of the lobster’s body, the cephalothorax, represents the fusion of the animal’s head and torso. It contains 6 to 8 pairs of ambulatory paws (used for locomotion), antennae, compound eyes, mandibles, and maxillae. In addition, there is another group of accessory appendages called maxillipeds. The maxillipeds are close to the mouth and help in handling food. The posterior part, the abdomen, is composed of six segments, the pleopods (appendages adapted for swimming), the telson, and the uropod. All these structures together constitute the swimming tail of lobsters. 

Not all Lobsters have claws

There are two types of Lobsters: claw Lobsters and clawless Lobsters. Claw Lobsters are commonly found in cold marine waters and include the American Lobster, a popular variety served in seafood restaurants.

Spiny Lobsters do not have claws. They do, however, have long, strong antennae. These lobsters are commonly found in warm water environments, such as the Caribbean and Mediterranean. As a seafood dish, they often appear on the menu as a Lobster tail.

Nervous system and body control

The Lobster nervous system is complex. It is made up of the brain ganglion and associated nerves with locomotion and sensory functions. 

The antennas help in the physical-chemical recognition of the surroundings and the eyes only grant sensitivity to light. Its vascular system is composed of the heart, pericardial chamber, and haemolymph ducts. These ducts run throughout the entire body. Its vascular pigment, hemocyanin. Thus, the Lobster blood has a slightly bluish colour due to the presence of copper. The copper assists in the function of carrying oxygen throughout the body. 

An important organ found in Lobsters is the hepatopancreas. With a greenish colour, this organ has both digestive and hormonal functions. The hepatopancreas regulates part of the animal’s metabolism. 

The main excretory organ is located in the cephalothorax, close to the brain ganglion, and is called the green gland. The waste resulting from digestion is expelled through the anus, located at the end of the abdomen below the uropod.


Lobsters, similarly to other crustaceans, have internal fertilization. Males have specialized legs to hold the female, releasing the male gametes onto her through a duct that connects the testicle to the environment. 

Once fertilized, the eggs are carried in a large, yellowish mass that adheres to the lower abdomen of the female. After a period of maturation, the nauplii (first larval stage) are released into the environment. They grow and change to another larvae stage, and lastly, they become a juvenile, similar to an adult, but reduced in size.

Life expectancy

Lobsters have an estimated life span of around 50 years. Research has shown that due to the presence of telomerase enzyme expressed in large quantities throughout the life of Lobsters, their telomeres, the terminal portions of the DNA, do not suffer shortening, which characterizes the cellular aging process. 

In this way, adults remain reproductively active and fertile. What drives the death of most Lobsters is predation and fishing, which occurs intensely since they are considered luxury items in human cuisine. 

A small number with advanced age can die from exhaustion during the moulting process. Moulting requires high energy to complete the formation of a new carapace. In some species, this process ceases after decades. Thus, the exoskeleton degrades over time, which can also result in the animal’s death. 

What do lobsters eat?

Although they have a reputation for being scavengers and even cannibals, studies of wild lobsters show that these animals prefer live prey. These bottom dwellers delight in fish and shellfish. Although lobsters can eat other lobsters in captivity, this behaviour has not been observed in the wild populations.

Biggest lobster in the world

The largest lobster on record was captured in 1977 in Nova Scotia. It weighed about 20 kilograms and measured nearly 1 metre. Since then, very few lobsters have reached such gigantic proportions. The slipper lobster, a type of clawless lobster, is usually only a few inches long. 

Cave worshipers

One look at a Lobster will tell you that long-distance swimming is not in its repertoire. Lobsters begin their lives on the surface of the water, going through a planktonic stage. As immature Lobsters develop, they eventually settle on the ocean floor, where their favourite home are caves and rocky crevices. 

Lobsters are not red

People often mistakenly think that Lobsters are red, but that is not the truth. Most Lobsters have a brownish-brown or olive-green colour in nature, with just a slight reddish tinge. 

The reddish colouration in a Lobster’s shell comes from a carotenoid pigment called astaxanthin. In most Lobsters, this reddish hue blends with other hues to form the Lobster’s natural colour profile.

Astaxanthin is heat stable while other pigments are not. When cooking Lobster, their coloured pigments are degraded due to the high temperatures. However, there is one pigment that is an exception, the bright red astaxanthin. Thus, a cooked Lobster get the bright red colour usually associated with living Lobsters.

The Importance of Habitat for Food

One of the factors that determine the choice of habitat is the presence of a suitable substrate. Lobsters are preferentially established in rocky environments. Typical Lobster habitat consists of rocks on a sand bed.  The presence of algae attached to these rocks is an additional attractive element. In this environment, Lobsters can use existing cracks or create real holes in the underlying sediment of the rocks.

The rocks provide support for starting the construction of the retreat and, on the other hand, serve as shelter roofs. The presence of fauna associated with sediments and algae can contribute to the Lobsters’ diet.

The ecology of young Lobsters is much less known than the diet of adults. 

A hygienic animal

Lobster cleans some of its appendages from time to time. The antennae are seized one after the other at their base by a bent buccal appendage (maxillipeds) and the animal then slides the antenna into this socket until reimplanted entirely above the maxillipeds. It uses the same technique for its large pincer. Lobsters regularly clean their abdomen, and more particularly the pleopods, with their last pair of legs.

Lobsters in Popular Culture

In addition to popular food, Lobsters have a long tradition in popular culture. There are several impressive sculptures created to resemble large crustaceans. 

Despite the 35 metres  “World’s Largest Lobster” in Shediac, New Brunswick, a reinforced concrete and steel structure created by Canadian artist Winston Bronnum, is not the largest lobster. That honour goes to a sculpture measuring approximately 62‘x 42’ x 51‘ erected in Qianjiang, Hubei, China in 2015; the second place is the “Larry the Lobster” in Kingston, SE, South Australia, which measures 59‘ x 45’ x 50‘.


In this post, we answered the question “Is Lobster a fish?”. We also understood and learnt more about the Lobsters biology and ecology.  

If you have any thoughts or doubts, feel free to drop us in a comment below!

Frequently Asked Questions (FAQs): Is Lobster a fish?

Where does Lobster live?

Lobsters can inhabit the rocky bottom of all seas, with depths varying from five to fifty meters.

What is the Lobster predator?

The main natural predators of this species group are large demersal fish, such as cod and julienne (Pollachius pollachius). Cannibalism has only been reported in captivity.

How do Lobsters die?

Lobsters major reason for death is predator attacks and fishing. Some individuals may die during moulting in advanced ages, as this process requires a lot of energy to be completed.

Is it possible to keep a Lobster in a tank?

Yes, it is possible to keep a Lobster in a tank. However, it is necessary to pay attention to the Lobster requirements. They need proper pH levels ranging between 6.5 to 8.5 and no measurable quantities of ammonia and nitrate. Additionally, it is important to provide plenty of space for your Lobster and also a planted background.

How do lobsters communicate?

Lobsters communicate using chemical compounds. They can use pheromones in their urine and detect these substances using their olfactory sensory structures in the antennae.

How is the lobster’s body split?

The body of lobsters and other crustaceans is divided into a cephalothorax, part of the body formed by the fused head and thorax, and abdomen. 

How many pairs of legs does a lobster have?

They are decapods – Thus, they have ten legs. Generally, both forelegs are modified and well developed for catching food, the claws. The main representatives of the Decapoda class are shrimp, crabs, and lobsters.


Factor, J. R. (Ed.). (1995). Biology of the Lobster: Homarus americanus. Academic Press.

Booth, J. D., & Phillips, B. F. (1994). Early life history of spiny lobster. Crustaceana, 271-294.

Schweitzer, C. E., & Feldmann, R. M. (2014). Lobster (Decapoda) diversity and evolutionary patterns through time. Journal of Crustacean Biology, 34(6), 820-847.

Felder, D. L., Álvarez, F., Goy, J. W., & Lemaitre, R. (2009). Decapoda (Crustacea) of the Gulf of Mexico, with comments on the Amphionidacea. Gulf of Mexico origin, waters, and biota, 1, 1019-1104.